1. Field of the Invention
The present invention generally pertains to handheld medical devices, and more specifically to high-speed electrically driven lancets; epidural catheter inserters; biopsy medical instruments, such as bone biopsy medical devices; vascular entry syringes and other catheterization needles. The invention is applicable to the delivery and removal of blood, tissues, medicine, bone marrow, nutrients or other materials within the body.
2. Description of Related Art
Vascular Entry:
Short-term or permanent central venous access, such as by catheterization, is sometimes associated with procedures such as hemodialysis, chemotherapy, bone marrow transplantation, long-term antibiotic therapy and parenteral nutrition. To perforin a catheterization, an internal vein, such as the internal jugular vein, is punctured with a single-wall puncture needle attached to a syringe (i.e., a central venous catheter introducer), thereby forming a subcutaneous tunnel to the vasculature. Once the needle is in place, a guidewire-dilator is advanced into the venous system through the subcutaneous tunnel. A catheter is then inserted through the lumen of the subcutaneous tunnel and advanced into the desired position.
There are many possible complications that make vascular entry difficult. For example, a clinician must locate and support the appropriate vein palpatively with one hand while the other hand positions the syringe and introducer needle proximally. The positioning of the proximal hand on the syringe, primarily for actuation of a plunger (for introducing anesthetics, saline and medicine, or for withdrawing blood) makes it very difficult to control the needle tip at the puncture site.
Moreover, the insertion force required for penetration of the needle into the desired position may also pose a challenge. For example, due to their elasticity and size, both skin and venous tissue can vary in the force required to penetrate. Female vascularization is typically smaller, compounding the difficulty of blood vessel entry. The needle insertion process, as performed by a skilled clinician, can be impeded by rolling of veins upon even slight tangential contact by the needle.
Procedures such as subclavian vein insertion and internal jugular venipuncture are also quite risky due to the force necessary for penetration of a needle into veins and arteries. For example, because the lung apex is close to the clavical and subclavian vein, the risk of overshooting and causing accidental pneumothorax is increased. To reduce the risk of overshooting, clinicians are advised to insert the catheterization needle and then “walk” it slowly against the edge of the collar bone. Since the applied force necessary to produce enough forward momentum to pass the overlying tissues can be relatively high, the procedure must be performed carefully and slowly. Unfortunately, because of this high force, a clinician has little time to react to stop the forward momentum immediately after successful venipuncture is achieved. In some cases, by the time a clinician can react to reduce the applied forward momentum upon overshooting the needle, pneumothorax occurs and air is immediately aspirated. At this point, advanced emergency intervention by specialized and trained assistants is required.
Advances, such as that disclosed by Yang et al. (Yang, M., Zahn, J. D., “Microneedle Insertion Force Reduction Using Vibratory Actuation”, Biomedical Microdevices 6:3, 177-182, 2004) rely on a reduction in microneedle insertion force by using vibratory actuation in the “kHz range”. Similar to the way a mosquito uses vibratory cutting at a frequency of 200-400 Hz to pierce the skin, Yang et al. discloses a mechanical actuator to control forces on the microneedle during insertion to minimize pain. However, Yang et al. rely on lateral motion to reduce the force which has been shown to cause thermal damage in vascular tissues. Additionally, Yang et al. provides no indication of the type of actuator and configuration of a device that would provide for such motion. Meanwhile, in the work of Podder et al., (“Effects of Velocity Modulation during Surgical Needle Insertion”, Proceedings of the 2005 IEEE, Engineering in Medicine and Biology 27th Annual Conference, Shanghai, China, Sep. 1-4, 2005), it is envisioned that for precise placement of surgical needles in soft tissue, an optimal insertion speed will minimize tissue and organ deformation. Unfortunately, while the work admits that optimal insertion occurs using a combination of a constant axial insertion speed with some rotational oscillation, it also admits that oscillatory motion increases the insertion force.
Therefore, a need exists for a central venous catheter introducer having a needle which is oscillated in an axial direction in short increments and at such a frequency as to reduce the force necessary for puncturing and thereby to reduce tissue trauma and produce a higher vessel penetration success rate.
Epidural:
Epidural anesthesia is a form of regional anesthesia involving injection of drugs directly into the epidural space. To begin the procedure, a needle is inserted from the outer layer of skin, through several tissues and finally placed within the epidural space, through which a catheter is passed. Local anesthetics are injected into the epidural space causing temporary loss of sensation and pain by blocking the transmission of pain signals through nerves in or near the spinal cord. The procedure can be unpleasant to the patient because of the high force levels required to penetrate the supraspinous ligament, interspinous ligament and ligamentum flavum. Often, because of this high force for penetration and an almost instantaneous change in resistance upon passing the needle into the epidural space (i.e., high forward momentum followed by instantaneous minimization of friction), a clinician will accidentally overshoot and puncture the dura. Upon puncturing the dura, a cerebrospinal fluid will leak into the epidural space causing the patient to experience severe post dural puncture headache, lasting from two weeks to several years. Significant leakage can cause enough intracranial hypotension as to tear veins, causing a subdural hematoma, and can cause traction injuries to the cranial nerves resulting in tinnitus, hearing loss, dizziness, facial droop, or double vision.
Currently, to minimize the possibility of a dura puncture, the epidural catheter insertion process is performed very slowly and with a 16-18 gauge, specially designed needle PA2, such as the one shown in FIG. 2 called a Tuohy needle 5. The Tuohy needle 5, has a curved tip 6, which decreases the “sharpness” at the needle and, therefore, makes accidental dura puncture more difficult. The needle also comprises an opening 7 at the tip for introducing or removing fluids and catheters. Unfortunately, this curved-tip design actually increases the force a clinician must use and makes it more difficult for a clinician to stop the forward momentum upon penetration of the dural space. Additionally, the Tuohy design increases the likelihood that a clinician relies on tactile feedback during penetration. In other words, during the insertion procedure a clinician will rely on feeling a “popping” sensation—indicative of passing the needle past the dural wall—to locate the tip of the needle and quickly stop the forward momentum being applied. Still, because penetration into other tissues, such as muscle, calcified ligament, or regular ligament may produce a similar popping, a clinician may not fully perceive the correct location of the needle tip.
Several alternate technologies have been developed that attempt to minimize the dura puncture risk, while also giving the clinician indication of successful epidural placement. For example, the detection method and apparatus disclosed in Patent Application Publication No. US 2007/0142766, the contents of which are incorporated by reference, relies on a spring-loaded plunger pushing a fluid into the epidural space upon successful entry. Accordingly, the clinician is given a visual indicator (i.e., the movement of the plunger as the fluid experiences a loss of resistance at the needle opening), and would cease applying forward force. Similarly, U.S. Pat. No. 5,681,283 also relies on a visual indicator to communicate successful entry of a needle into a cavity to the clinician. Unfortunately, while a visual indicator is a positive advancement, the actual cause of the accidental dural wall puncture—that is, the high force applied by the clinician against the needle to pass through the various tissue layers—is not addressed.
Therefore, there exists a need to provide a tool that reduces the puncture force of a needle, such as a Tuohy needle, and enables a clinician to perform a more controlled entry into the epidural space, thereby reducing the possibility of an accidental dura puncture.
Biopsy:
Biopsies are procedures in which an instrument is used to remove tissue samples from within the body. The collected samples may then be analyzed for disease, or in some cases, screened for compatibility between patients for tissue transfusions. For example, in the case of a bone biopsy, it is common to remove samples of the central tissue of bones, referred to as marrow, which is surrounded and protected by the outer layer of bone called the cortex, using a specialized manually operated collection tool, such as a JAMSHIDI®, available through Cardinal Health of McGaw Park, Ill. Bone marrow examination is used in the diagnosis of a number of conditions, including leukemia, multiple myeloma, anemia and pancytopenia. Beyond simply being drawn for purposes of diagnosing, bone marrow may also be harvested and transferred either allogenically or autologously to provide hematopoietic stem cells used to restore a patient's immune system after chemotherapy treatments.
Because the marrow is surrounded by the cortex, which is considerably harder than the trabecular bone layer and marrow, a clinician must exert a high force to introduce a biopsy instrument to penetrate the cortex. Several damaging effects can happen when high force is used to puncture through hard bone. Still, several conventional tools exist for the purpose of collecting samples of bone marrow. Typically, the tools are quite simple, such as the one shown in Prior Art FIG. 1, comprising a handle portion (not shown), and a hollow cannula 1 surrounding a stylet 2 attached to the handle portion such as that disclosed in U.S. Pat. No. 6,443,910 (Krueger et al.), which is hereby incorporated by reference. In other references, such as U.S. Pat. No. 5,885,226 (Rubinstein et al.), the contents of which are incorporated by reference, the stylet is referred to as an “inner trocar” or simply, an “introducer”.
To penetrate through hard tissues, such as bone, a clinician holds a manual biopsy tool PA1 such as that shown in Prior Art FIG. 1 at the handle (not shown) and pushes the cannula 1 and stylet 2 through the bone, finally reaching the marrow. To reduce the exertion force necessary by a clinician on the device to achieve penetration of the cannula and stylet through bone, the distal tip 3 of the inner stylet or trocar is sharpened and has an angled, chisel-like face 4 which reduces the surface area. Additionally, a distal end 1′ of the hollow cannula may be serrated and sharpened to aid in penetration and severing of tissues for sample collection (i.e., coring). While some reduction in force is attained using these kinds of handheld biopsy devices, clinicians find themselves not simply pushing with a longitudinal force, but also with twisting motion for successful penetration and sample collection. This twisting motion causes the tool tip to scrape and grind with the sharp tip during penetration causing fragments of the bone to break away in shards and small pieces. Unfortunately, because the tool is limited in this simple handheld design, the method to use the tool is also limited because the twisting and constant longitudinal force may result in a bone fracture, or a wound site that is not optimally formed for fast and efficient healing. Additionally, because the size of the biopsy sample is important, design changes such as larger cannula have been offered. Unfortunately, when a larger cannula is used, the result is a higher force necessary to penetrate the bone. Ultimately the larger size results in extreme pain and trauma for the patient despite local anesthesia, as disclosed in United States Patent Application Publication No. 2008/0139961 (Slama et al.). In U.S. Pat. No. 6,273,861 (Bates et al.), which is hereby incorporated by reference, it is disclosed that manual biopsy devices are hindered because the operating clinician must have a great deal of control and strength to advance the stylet through the hard cortex bone material. As a result, it takes a great deal of force to penetrate through it. Therefore, the cannula is advanced relatively slowly resulting in poor cutting action and surrounding tissue collapse.
Several advances that introduce automatic triggering mechanisms capable of increasing the speed at which the sharp tip of a device pierces through tissue have been attempted to reduce the pain experienced by patients during biopsy procedures. By automating the function of introducing the sharp tip of the devices into a patient, these devices attempt to replace the large force that a clinician must automatically apply on the tool with a quick moving, sharp tip traveling through tissue, thereby reducing pain for the patient. According to the '861 patent, these rapid fire “gun” type biopsy tools reduce the dexterity and motor coordination necessary and produce a quick, clean cut. For example, advances that allow biopsy devices to operate in a controlled “firing” manner in which the tissue is penetrated by the sampling needle at a very high velocity are disclosed in U.S. Pat. No. 7,018,343 (Plishka). Additionally, United States Patent Application Publication No. 2008/0103413 (Cicenas et al.) discloses a pneumatic, mechanically driven apparatus which is used to advance a hollow cutter at a relatively rapid speed to a first position and then advance the cutter at a relatively slower speed, while rotating the cutter to sever the tissue. Still, according to the '861 patent, these, or “gun” type biopsy devices, are limited in that many are spring-loaded and must be manually cocked, requiring a large force. Also, the resulting “firing” of these mechanically triggered devices are known to produce a jerking motion which is a problem both to the physician and patient.
While some reduction of force may be attained by quickly firing the sharp portion of a biopsy device into a patient, they are limited by the aforementioned problems. With respect to bone biopsy devices, but applicable to other medical devices, as disclosed in U.S. Pat. No. 6,730,043 (Krueger), factors, such as balancing the ability of bone biopsy devices to cut out samples in a consistent manner without unnecessary damaging forces exerted on the sample, combined with accommodating patient comfort by reducing the need for multiple-site-sampling, has proven challenging. Therefore, a need exists to overcome the challenges not addressed by conventionally available technologies that reduces the force necessary for penetration of a sharp medical element of a medical device through tissue and also has the ability to deliver or retrieve materials subcutaneously.
Specifically, a need exists in the medical device art for an improved medical device having a sharp element that is vibrated sonically and ultrasonically, thereby reducing the force required to penetrate tissue, reduces the amount of resulting tissue damage and scarring, improving vessel access success rate, minimizes catheter wound site trauma and, most importantly, improves patient comfort.